Lubricating oil



Patented Feb. 25, 1941 UNITED "STATES PATENT OFFICE 2,233,203LUBRICATING on.

Marcellus T. Flaxman, Wilmington, Calit, assignor to Union Oil Companyof California, Los Angeles, Calif., a corporation of California NoDrawing.

Application May 3, 1938,

Serial No. 205,725

. 16 Claims. (Cl. 252-39) This invention relates to lubricating oils andparticularly to mineral lubricating oils adapted for use in severeservice internal combustion engines such as Diesel engines and high.output aviation engines.

The object of the invention is to provide mineral lubricating oils whichwill be highly stable against deterioration in use and will largelyoverin the oil, at least in the proportions in which they are used forthe present purposes.

STATEMENT or INVENTION Primarily, the present invention resides in theemployment in appropriate mineral lubricating oils of oil-soluble ordispersible metal soaps, such as alkaline earth metal soaps, or othersuitable oil-solub'e or dispersibe soaps, of acids which will bereferred to here as pine acids or rosin acids or abietic acids. Thesesoaps are to be added to suitable mineral lubricating oils (preferablynaphthenic base oils) hereinafter described in small proportionsinsufiicient to im- 1 within limits of about 0.5% to 2.5% or 3%, orbetween about 1% and 2%, e. g. around 1.5%. The invention also resida inthe use additionally of herein indicated types of soaps of what mayother suitable high molecular weight fatty acids, and the inventionfurther resides in the use of all these various soaps where they arealso chlorinated or sulfurized or sulfo-chlorinated. l he use ofchlorine and sulfur is to impart certain oiliness and extreme pressurecharacteristics which are desirable.

To obtain the advantages of sulfur, it is also desirable to employ anaphthenic base mineral lubricating oil naturally containing sulfursufficient to meet the requirements, for example from about one-halfpercent sulfur to 4% or 5% sulfur. .The use of such. sulfur-bearing oilsis valuable to offset corrosive conditions which are imparted wherechlorine is present andespecially to offset tendencies toward corrosionby,

organic acids of highly corrosion-sensitive alloy bearings, for examplecadmium silver bearings, where the soaps tend to hydrolyze and promoteon corrosive conditions. The invention therefore part a grease-likeconsistency, and preferably be referred to as pine fatty acids, or-soapof resides also inthe employment of pine acid or rosin acid soaps of theindicated types in mineral lubricating oils containing appreciablesulfur content as indicated, either naturally or by sulfurization of thesoaps themselves. About 1% to about 3% combined sulfur such asnaturallyoccurring sulfur represents ordinarily a preferable range.

The invention also resides in such soap-containing oils wherein a-smallacid number exists, such as 0.2 to 0.5 as hereinafter indicated, wherebyoil-solubility is improved and gelation in presence of small watercontent is avoided.

DEFINITIONS Where the term "rosin acids" or pine acids" is used, I meanprimarily abietic acid which ordinarily predominates in rosin and rosinoil and in oils which are marketed as tallol or tall oil, and may bepresent in other resins. While these materials include kindred acidssuch as d-pimaric acid and sapinic acids, and apparently also variousisomers and polymers of these acids, the term abietic acid in general isintended to include also the mentioned variations. The term "pine acidsor rosin acids likewise is intended to signify the various abietic and'kindred acidic materials and other saponifiable materials found inrosin, rosin oil, tall oil and I the. like. Apparently all of thesematerials are valuable for the purposes here stated, and it is thereforepossible, and within the scope of this invention, to produce soaps fromthe separated abietic acids or other indicated kindred acids or estersor from the rosin or rosin oil or tall oil themselves, and thesematerials are intended to be included in terms such as rosin acids" andpine acids".

For the purposes of this disclosure abietic acid '(CmHzoCOOH) is assumedto have the following probable structural formula which is commonlyaccepted by many investigators as being representative of what iscommonly known as abietic acid:

coon

1120 f \CH2 l tive of present chemical knowledge on the sub ject and forthe purpose pf making as full and clear a disclosure as possible. I

With further reference to the terms rosin acids and abietic acids, it isintended to in-- clude all those rosin materials which contain acidsakin to abietic acid and produce the desired soaps of the presentinvention. As is well known, rosin is the relatively high melting pointresidue obtained from the distillation of natural crude turpentine fromliving trees and known s gum rosin, or from the steam distillation orsolvent extraction of the wood of pines and firs, such as cured or fattypine .stumps, and known as wood rosin.

spond generally with those from, the livingtrees.

but diifer in some particulars not clearly understood. However all ofthese rosin oils and rosins contain abietic acids and may be used forthe.

present purposes. Apparently the abietic acids which are distilled overin the rosin oils are of lower'molecular weight than the polymersremaining in the rosin bottoms; of the different abietic acids may beisomers of one another. The constitution above given for abietic acidsis furnished as merely representative and there are undoubtedly manyso-called abieticacids of varying constructions.

It is generally understood that abietic acid as such does not exist inthe natural secretions and that other constituents, possibly isomers,are present having about the same composition as abietic acid itself,namely C19H29COOH. In any event, heat treatment and also acid. treatmentyield abietic acid, and it would appear that heavier heat treatmentyields various isomers of abietic acid and probably polymers thereofalso.

These acids, which are. commonly referred to as abietic acid and arehere generally considered 'as consisting of abietic acid and itspolymers principally but containing also d-pimaric and sapinic acids,are in general the acids intended when the term rosin acids is employed,this term including also the various isomers and polymers of these acidsand kindred acids present in or obtainable from rosin.

With respect to the commercial product known as tall oil, this is saidto be define-d as awaste material or by-product which is recovered fromthe wood of coniferous trees during the process of conversion-of thewood fibre into cellulose b the -so-called sulfate or Swedish processfor cellu lose pulp making. The residual waste liquor ob? tained fromthe process after the separation of the cellulose therefrom separatesinto two layers,

the top layer of which is skimmed off and represents the crude tall oil.It is an oil of a strong tarry odor before purification and has chemicalproperties between those of fatty acids and those of resinic acids dueto the fact that the tall oil always contains both fatty acids andresinic acids as two constituents. If desired,'the tall oil may bepurified by distillation or by any other known or preferred process.Either the purified The turpentine passes off under low temperaturedistillation conditions or the crude tall oil may be employed in thecompounds of the present invention.'

The percentagesof fatty acids in tall oil vary from about 20% to about50% or 60%, and the rosin acids vary from about 70% to about 20%, theremainder being sterols; other higher alcohols and hydrocarbonsapparently. The fatty acids apparently are characteristic pine acids Iand not necessarily those commonly implied in the term fatty acids, andmay be designated by the term pine fatty acids. This fatty acid contentis largely unsaturated as indicated by the iodine number, theunsaturation apparently being of the oleic acid type. Presumably theseunsaturated acids correspond largely with oleic acid or the closelyrelated acids such as linoleic and linolenic, and possibly also in minorproportions with such ligher acids as myristoleic and palmitoleic andheavier acids such as the elaeog stearic, and erucic acids. However,since oleic acid is known generally to predominate in nature, these pinefatty acids as a whole are herein generally considered from thestandpoint of oleic acid constitution.

- OPERATING PROCEDURES The preparation of soaps of abietic acid or rosinacids will be considered from the standpoint of calcium soaps made bythe saponification of rosin, or rosin purified to increase the abieticacid content, or rosin oil, .whichwill in eneral be also applicable tothe preparation of such soaps from tall oilor purified or partiallypurified or segregated rosin acids such as commercial abietic acid,where available. In the saponification of ro'sin to produce calciumsoaps thereof, or in the saponification of rosin oils or the like, therosin or rosin oils preferably will .be dissolved at suitably elevatedtemperature, for example 250 F. in the case of rosin, in an appreciablequantity of the mineral lubrieating oil to be used in preparing thefinal product. For example 1 to 10 volumes of lubricating oil based onthe rosin may be employed. To

this oilsolution of rosin or rosin oil will be introduced preferably anexcess of hydrated lime',

(about 15% to 20% based on the rosin or rosin oil) and if desired asmall quantity of water such as one-tenth'of 1% of the total. Thismixture, will then be raised -to.a temperature of about 275 F. or in therange of 250 F. to 350 F. and maintained for a period of about two tofive hours to eifect neutralization of the rosin acids to the desiredextent. This neutralization may be complete if desired or it may be suchas to leave any desired or appropriate acid number. In employing 1 or 2volumes of oil to 1 volume of rosin or rosin 'oil, the resultant masswill be more in the nature of a grease and this mass may 'then'bediluted with more mineral oil to yield a suitable oil-soap concentrateof any desired soap content such as from 5% to 40% soap. I

On the other hand, the total amount of oil desired in the concentratemay be added before saponification is undertaken and the entire masssubjected to the above indicated temperature range to obtain thedesired-extent of neutralization. Ordinarily the time forsaponification-will be greater than with the smaller amount of mineraloil. After the desired degree of neutralizat ion has been effected, themass will be brought to a temperature of around 325 F.'to 350 F. toinsure easy filtration or separation of solids and also to accomplishsufiicient dehydration to insure against any subsequent tendency to gel.For the purpose of removing solids centrifuging may be employed, or asmall quantity of diatomaceous earth or other suitable filter aid willbe supplied to the oil-soap mass to insure better removal of excess limeand the hot mass then filtered through a filter precoated with a smallquantity of diatomaceous earth or other appropriate filter aid. In theuse of filter aids care should be taken to avoid the use of those of acharacter or in quantity sufiicient to efiect substantial removal of thesoaps from the oil as by adsorption. These filtrates when cooledconstitute oil-soap concentrates which may be subsequently employed foraddition to further amounts of the selected mineral lubricating oilstock in preparing final blends containing the indicated desired amountsof soaps, for example around 1% 'to 2% or more, particularly in theorder of about Water and acid. contents 1.5% of soap, the water contentshould be under 0.1% or preferably under about 0.05%.

However, it has been found that by effecting an M acid number in thesoap. corresponding to an acid number in the final blend of about 0.2 to0.3 or in some cases 0.4 or 0.5, the water tolerance of the-blends isincreased. For example a blend having an acid number of .36 was highlyresistant or tolerant toward the presence of 0.1% to 0.2% water withoutgelation. Also, another function of such free acid is to insureretention of the soaps in the oils. An acid number of 0.35 to 0.5insures against the substantial formation of heavy bodied-or viscousemulsions with the larger amounts of moisture.

By acid number is meant the amount of KOI-I in milligrams necessary toneutralize the acidity in one gram of the compounded product, and

refers to the A. S. T. M. Method B for Com-.

pounded Petroleum Products as distinguished from Method A for PetroleumProducts. These methods are found in the A. S. T. M. Standards for 1936test number D188-2'7T described on pages 629 to 631 It is to beunderstood thatthe acid numbers here given relate to final blendscontaining about 1.5% calcium rosin acid soaps calculated as calciumabietate or kindred soaps produced from rosins o'r rosin oils and thelike.

In neutralizing rosin or rosin oil or rosin acids or tall oil, thedesired acid number may be obtained by limiting the quantity of hydratedlime employed, or by limiting the heating time to effect only thedesired degree of neutralization, or more conveniently by adding to aneutral concentrate prepared with an excess of lime a suitablycalculated quantity of rosin or rosin oil or commercial abietic acid orother material containing the desired abietic acid. The acid number inthe concentrate is of course adjusted so as to yieldthe desired acidnumber in the final blend above indicated.

Soaps In the use of tall oil, similar procedures are followed in thepreparation of the soaps, but the resultant soaps, instead of beinglargely rosin acid soaps as is the case where rosin and rosin oils areemployed, will be a mixture of rosin acid soaps and fatty acid soaps byreason of the fact that tall oil, as heretofore outlined, contains notonly rosin acids, particularly abietic acid but also fatty acidsobtained from the coniferous wood employed. Since tall oil varies incontent of fatty acids (pine fatty acids) and rosin acids, as previouslyindicated, the mixed soaps will vary accordingly. There are certainadvantages in the use of these mixed soaps in that they act as commonsolvents for each other and the fatty acid soaps appear to serve tostabilize the rosin acid soaps and retain them in the lubricating oil.In the use of these mixed soaps the total soap is considered incalculating the soap content in the concentrate or final blend. In somecases, the commonly known fatty acids may also be employed with therosin acids or abietic acids herein described when preparing soaps ofthis invention.

In the preparation of soaps of the acidic mate-' rials herein described,the calciumsoaps are preferred insofar as present developments areconcerned because they are adequately oil-soluble under the conditionsdescribed and are more or less conveniently prepared. Likewise they arehighly efiicient for the purposes described. On the other hand, theinvention is not limited to the use of calcium soaps but may employ insome cases other soaps particularly soaps of aluminum, magnesium andzinc. Also it is possible to use soaps of sodium, potassium, tin,manganese and the like for certain purposes and likewise soaps oforganic bases such as amyl amine, cyclo hexyl amine, morpholine,triethanolamine and the like.

. It is to be understood, however, that none of these soaps are nowconsidered to be the full equivalents of calcium soap. In some instancesthese various other soaps may be used in various combinations with eachother and with the preferredcalcium soaps; for example triethanolaminesoap may be used with the calcium soap.

As a possible source of abietic acid or other osin acids in thepreparation of soaps herein indicated, it may be desirable in someinstances to employ as pure rosin acids as possible. These may beprepared from methyl esters of abietic acid or mixtures of rosin acids,which esters are available on the market. This can be accomplished byhydrolyzing the esters in the presence of glycerin with an alkalihydroxide such as potassium hydroxide, dissolving in water, washing withpetro- I leum ether to dissolve out unsaponified materials from thealkali metal soap, adding excess dilute sulfuric acid or otherappropriate mineral acid to precipitate-out the resultant abietic acidor rosin acid mixture, efiecting a solution of resultant rosin acids inpetroleum ether or similar light solvent whereby it'may be separatedfrom the aqueous solution, recoveringthe rosin acid solution, removingthe light solvent therefrom and used in paper'sizing, other wood rosinsand the gum rosins and corresponding rosin oils. The saponifiable esterspresent may also be included as acceptable materials; these of courseraise the saponification number above the acid or neutralization number.These various rosin materials vary in acid content from about 80% to 90%(calculated as abieticacid) on the average, and from acid numbersofabout 150 to about 170 on the average (150 acid number equals about81% acid and 170 acid numberequals about 92% acid).

BLENDING For the production offinal blends according to the presentinvention, the concentrates above de scribed are added to lubricatingoils of the characters herein defined, preferably at temperatures around120 F. to 130 F. or 140 .F. in proportions to effect the final desiredsoap content, for example 1.5%, by. simple agitation. The concentrateitself may have been prepared with the ordinary California or'otherordinary naphthenic base oil containing around 0.5% of sulfur asheretofore described, or with the high sulfur naphthenic base oilsheretofore described, or with any suitable blend of the ordinarynaphthenic oils and the high sulfur naphthenic oils mentioned, forexample to yield from about 1% to almost 3% sulfur as an ordinarilypreferable range. Likewise the oil base to which the concentrate isadded may consist of one. of the ordinary California or other ordinarynaphthenic mineral lubricating oils or the high natural sulfurnaphthenic base oils -or any suitable adjusted blend thereof containingthe desired sulfur content.

With respect to the particular high sulfur content naphthenic base oilswhich are usable, I

vmay mention as appropriate the Santa Maria Valley (California)lubricating oils, the Smack-' over (Arkansas) oils, the Spindletop(Texas) oils and certain Mexican oils having the same generalcharacteristics and high sulfur content. These oils after ordinaryrefining and acid treatment contain ordinarily from about 2.5% sulfur to4% or 5% sulfur and are therefore very desirable for the presentpurposes. Similarly shale oils which contain sulfur contents as high as6% or 7% may also be employed in obtaining suitable blends. Againsolvent extract fractions of sulfur-contain ing petroleum lubricatingoils may be employed or added to increase sulfur content. These solventextracts produced by selective solvent treatment of mineral lubricatingoil stocks are well known and possess high sulfur concentration byreason of the removal of the natural sulfur-bearing materials from thestocks. The higher the sulfur content of the stock, the higherthe sulfurcontent of the extract. In general the final sulfur contents of theblended oils vary from about 0.5% sulfur to as high as 4% to 5% sulfur.Where the oils are to be employed with highly corrosionsensitive alloybearings, such as cadmium silver bearings, sulfur content preferablyshould be greater than in the caseof Babbitt bearings, and likewise whenadded oiliness and extreme pressure characteristics are required asis-usually thev about 3.25%. Ordinarily a lighter S. A. E. grade acts toovercome corrosive tendencies which may result 'from hydrolysis of thesoaps or may result from the presence of other corrosive materials addedto the blend or to the soap molecule, and

also serves to impart added oiliness and extreme pressurecharacteristics. Such other materials for example, in addition to acidsdeveloped by hydrolysis or otherwise, may be represented bysulfochlorinated fatty oils or the like.

Typical oils which may be used for producing concentrates and finalblends according to the present invention are found in the followingCalifornia naphthenic base type S. A. E. 30 oil and the Santa MariaValley naphthenic type S. A. E. 30 lubricating oil. 4 I

The California naphthenic S. A. E. 30 011 possesses the followingcharacteristics:

Gravity A. P. I. at 60 F Color N. P. A 3 Flash C. O.- C ,F 380 Fire test0. o. c -F 425 Viscosity at F. Saybolt Universal 571.5 'Viscosity at 210F. SayboltUniversal'. "55.3 Pour point l F 5 Acid number (Method A) 0.04Viscosity index 13 Viscosity gravity constant 0.877 Sulfur by weight v0.5% Indiana oxidation test:

Hours for 10 mg. per 10 gm. sample 15 Hours for 100 mg. per 10 gm.sample- 35 Ash I Nil Carbon residue teristics was prepared by treatmentwith 60 pounds of 98% of sulfuric acid per barrel:

This-oil contains natural sulfur content or thereof will possess asmaller sulfur content, for

Gravity A. P. I. at 60F 19.0 Color N. P. A 2.4 Flash 0. o. c F 390 Firepoint C. O. C F 4 50 Viscosity at 100 F. Saybolt Universal sec 590Viscosity at 210 F. Saybolt Universal sec 56 Acid number (Method A) 0.04Viscosity index ;l 25 Viscosity gravityconstant 0.8'8'9 Sulfur by wei ht3.25%

Indiana oxidation test Hours for 10 mg. per 10 gm. sample' 22 Hours for100mg. per 10, gm. sample 40 Pour point ?F +15 example about 3%, and aheavier S. A. E. grade ordinarily will have a somewhat greater sulfurcontent, for example about'3.5%.

Arr average blend of the two oils of the types above described'in equalquantities possesses the. following characteristics, this table coveringa blend withand without 1.33% calcium rosin acid soaps from "commercialabietic acid:

Blend with Blend 1.33% calcium without abietate soap Gravity A. P. I. at60 F 19. 2 19. 8 Viscosity, Saybolt Universal seconds at 1 F 732. 8 550Viscosity, Saybolt Universal seconds at 210 F 58. 7 55 Viscosity index 0l5 Viscosity gravity constant... 0. 836 07 884 Flash, 0. O. 0. F 370 370Fire, 0. O. 0. F.-- 435 445 Pour point. F... 0 +5 Color, N. P. A V4 Acidnumber (mg.KOH/g.). '3. 6 04 Sulfated ssh, percent by weight 28 NilSulfur by weight 1.88 l. 88

Method B.

"Method A.

Addition agents as herein employed and necessary for these purposes aresuch as will increase the base oil viscosity only to an inconsequentialextent, for example such as indicated in one of the above tables givingdata on blends with and without soap. It is to be understood,

of course, that a slight viscosity increase such as that imparted by theuse of 1.33% of calcium arbietate offers no objection.

In addition to using rosin acid soaps of types above indicated. it mayalso be desirable to sulfurize, or chlorinate, or sulfo-chlorinate suchrosin acids and make the soaps therefrom. BY sulfurizing, the beneficialeffects of sulfur in reducing bearing corrosion may be obtained in thesoap, and by chlorinating the increased film strength imparted bychlorine may thereby be obtained in the soap. Both advantages may beobtained by using mixtures of sulfurized and chlorinated materials, orboth sulfur and chlorine may be added to the acid molecule as bychlorinating and then sulfurizing, or vice versa, or by treating with asulfur chloride. For example, sulfurization under mild conditions toeffect partial saturation may be followed by chlorination to effectfurther-saturation. The effects of chlorine may be otherwise obtained byusing addition agents containing chlorine as hereinbefore indicated,including chlorinated esters such as chlorinated methyl ester of abieticacids, and the valuable effects of sulfur may be otherwise obtained byadding sulfur-bearing materials such as sulfurized oils or fatty oils,organic thio compounds such as organic thiophosphates, sulfurized estersor sulfo-chlorinated esters, such sulfur-bearing methyl ester of abieticor other suitable acids, and the like.

A further use for soaps of .abietic acids and other rosin acids is found'in their fiuidizing properties for grease-like mixtures and othermixtures containing other soaps. For example, a blend of a light Westernmineral lubricating oil distillate having a viscosity of 100 secondsSaybolt Universal at 100 F. containing 4% aluminum stearate formed a gelwhich was reduced to a highly fluid stable oil by the addition of 1%by'weight of calcium soaps of tall oil. This suggests the use of calciumabietates in conjunction with other soaps having especially valuableproperties in severe service engines where such soaps otherwise tend toseparate from the oil or tend inordinately to increase the visdosity ofthe base oil. I have found, for example, that one-quarter to one-halfpercent of calcium soaps of commercial abietic acid retains as muchas'one percent of commercial calcium stearate in stable dispersion orsolution in lubricating oils. The present invention however is notintended to extend to'those specially treated and modified rosin acidproducts which have high grease-setting or excessive gelling characteristics and therefore would impart excessive viscosity to liquidmineral lubricating oils intended for uses such as internal enginelubrication here described. Such special materials include a rosinproduct known as Hyex as described invthe Lister Patent 2,103,204 andBritish Patent4'71,629, and other specially prepared. or treatedmaterial such as that described in the Brennan et al. ,Patents 2,042,035and- 2,072,628. On the other hand the materials used in the presentinvention are predominately unmodified rosin acid compounds and do notsubstantially increase viscosity in the indicated amounts.

The foregoing disclosures have been furnished for the purpose ofindicating preferred and other forms of the invention as they arefnowunderstood by applicant, and are to be considered'as illustrative andnot as limiting.

I claim:

1. A lubricating oil for severe service internal combustion enginescomprising a naphthenic base mineral lubricating 011 containing betweenabout 1% and 2% of an oil-soluble soap of rosin acids exclusive of thosehaving high greasesetting properties," the-soap having the property of.controlling ring sticking in heavy-duty internal combustion engines andfree from the property of imparting substantial viscosity increase tothe base oil in the stated amounts.

2. A lubricating oil for severe service internal combustion enginescomprising mineral naphthenlc base lubricating oil containing a stableoilsoluble soap of rosin acids in quantity between about 1% and 3%sufficient to overcome ring sticking and the deposit of gummy, resinousand varnish-like materials in the engine but insufii cient tosubstantially increase the original viscosity of the naphthenic baselubricating oil or impart grease-like characteristics.

3. A lubricating oil accordingto claim 1 wherein the soap is a calciumsoap.

4. A lubricating oil according to claim 2 wherein the soap is a calciumsoap.

5. A lubricating oil for internal combustion engines comprisingnaphthenic base mineral lubricating oil naturally containing at leastabout 0.5% sulfur and an oil-soluble. soap of rosin acids in quantitygreater than 0.5% butinsufiicient to materiallyincrease the originalviscosity of the naphthenic base oil.

6; A lubricating oil for internal combustion engines comprising 'asulfur-containing naphthenic base mineral lubricating oil and betweenabout 1% and 2% of an oil-soluble soap of rosin acids, the soap beingpresent in quantity to control ring sticking in heavy-duty internalcombustion engines and free from the characteristic of impartingsubstantial viscosity increase-to th base oil in the indicatedproportions. 'I. A lubricating oil according to claim 1 wherein the soapcontains at least one of the elements chlorine and sulfur.

8. A lubricating oil for severe service internal combustion enginescomprising a mineral lubricating oil containing between 1% and 2% of anoil-soluble stable'soap of rosin acids, the mineral lubricating oilhaving an acid number of at least about 0.2 by the A. S. T. M. Method Band havin good solvent power for the soap, the soap being present inquantity to control ring sticking in 6 heavy-duty internal combustionengines and free from the characteristic of imparting substantialviscosity increase to the base oil in the indicated proportions.

9. A lubricating oil for. internal combustion engines havingnon-corrosive characteristics toward alloy bearings highlycorrosion-sensitive to organic acidity comprising a naphthenic basemineral lubricating oil having a sulfur content in excess of about 1%and containing between about 0.5% and 3% of an oil-soluble metal soap ofrosin acids containing rosin acids imparting an acid number to the oilbetween about 0.2 and 0.5,-the soap being present in quantity sufllcientto overcome ring sticking in heavy duty internal combustion engines andinsuflicient to impart substantial viscosity increase to the base oil.

. 10. A lubricating oil according to claim 9 wherein the soap is acalcium soap.

11. A lubricating oil for internal combustion engines of predominantlynaphthenic characteristics containing-between 0.5% and 3% ofoilsoluble'soap of rosin acids possessing free acidity, the oil havingan acid number between about 0.2 and 0.5 and containing less than about0.1% water, the soap being present in quantity to control ring stickingin heavy-duty internal combustion engines and-free from thecharacteristic of imparting substantial viscosity increase to the baseoil in the indicated proportions.

12.A mineral lubricating oil for internal com bustion engines being freefrom organic acid corrosion characteristics, towardhighly'corrosionsensitive alloy bearings and free from greaselikecharacteristics, comprising a naphthenic base mineral lubricating oilpossessing a natural sulfur content in excess of about 1% and containingmore than 0 5% .of calcium 'soap of rosin of about 0.5% sulfur and amixture of oil-soluble acids, the oil having an acid number by the 'A.S. T. M. Method B in excess of about 0.2.

13. A lubricant comprising a naphthenic base mineral lubricating oilnaturally. having a sulfur content in excess of about 0.5% and a calcium5 soap of rosin acids, the soap being present in quantity suiiicient toovercome ring sticking in heavy duty internal combustion engines andinsuflicient to impart substantial viscosity increase to the base oil.10

14. A lubricating oil for heavy-duty internalcombustion enginescomprising v a. naphthenic base mineral lubricating oil containingbetween about 0.5 and 3% of a mixture of calcium soaps of rosin acidsand calcium soaps of pine fatty 1 acids.

15. A lubricatingoil for heavy service internal combustion enginescomprising a naphthenic base mineral lubricating oilcontaining in excessmetal soaps of rosin acids and of pine fatty acids in amounts in excessof about 0.5%, to overcome valve sticking and deposits of resinous andvarnish-like materials, and insufilcient to materially increase theviscosity of the original 5 naphthenic base oil.

16. A lubricating oil for heavy-duty internal combustion enginescomprising mineral lubricating oil containing from about 0.5%-to 3% ofoil-' soluble soap of rosin acids, the soap being present a in amountsufiicient to overcome ring sticking in an engine butinsuificient toincrease substantially the original viscosity of the base lubricatingoil employed and being free from char-'- acteristics of impartinggrease-like characteris- 3 tics to the oil inthe indicated proportions.

MARcELLUs' T. FLAXIVIAN.

